This invention relates to a machine tool incorporating a processing station and at least one power driven feed system to move a workpiece and/or a machining tool in the direction of an axis of travel relative to the processing station. The machine tool has at least one directional guide with a power driven carriage that moves in the direction of the axis of travel, and carries at least one clamping device for a workpiece and/or at least one holder for a machining tool.
Such a machine tool may also incorporate at least one motorized feed system by which a workpiece and/or a machining tool can be moved in a plane defined by first and second axes of travel relative to the processing station. The machine has two directional guides of which the first directional guide moves a first power driven carriage with at least one workpiece-clamping device and/or at least one machining tool holder in the direction of the first axis of travel, while the second directional guide is provided with a second carriage on which the first carriage and at least one workpiece platen supporting a workpiece can be moved along the second axis of travel.
A machine tool of the general type mentioned above, in the form of a punch press, is described in DE-A-38 18 001 (U.S. Pat. No. 4,951,375). That machine employs as its first carriage a rigidly constructed slide which is stationary in the direction of a first axis of travel and movable in the direction of a second axis of travel. Along the first axis of travel, the slide drives a single, moving workpiece support rail which is provided with claw-type holders or clamps for the workpiece to be processed and with tool cartridges for holding machining tools.
Moving the workpiece support rail relative to the rigid slide carrying it positions the workpiece which is held by the claws associated with the workpiece support rail in the direction of the first axis of travel. That relative movement in the direction of the first axis of travel may also bring the machining tools mounted on the workpiece support rail into an operational and, respectively, switching position adjacent the processing station of that prior art machine.
The workpiece support rail of the punch press illustrated in DE-A-38 18 001 (U.S. Pat. No. 4,951,375), to carry this volume of components, tools and workpieces, must be designed for moving a relatively heavy weight on the associated rigid slide. It is also particularly important to remember that optimal operation of that prior art punch press requires a very precise positioning of both the workpiece clamped on the workpiece support rail and the tools mounted on that workpiece support rail. Accordingly, the workpiece support rail employed in the earlier design has a relatively large cross section and a highly rigid structure. It also bears considering that to operate the prior art punch press, the workpiece support rail has to be moved in the direction of the first axis of travel.
A machine of the second type mentioned above is currently being marketed by xe2x80x9cTRUMPF GmbH+Co. KGxe2x80x9d of 71254 Ditzingen Germany, under the model name xe2x80x9cTRUMATIC(copyright) 500 ROTATIONxe2x80x9d. In terms of the first directional guide of its feed system, this machine essentially follows the prior art design illustrated and described in DE-A-38 18 001. Specifically, the xe2x80x9cTRUMATIC(copyright) 500 ROTATIONxe2x80x9d employs as its first carriage a rigid slide which is stationary in the direction of the first axis of travel. The slide is connected to equally rigid supports, which extend in the direction of the second axis of travel to form a unitary overall rigid structure. A workpiece holder in the form of a platen is mounted on the above-mentioned rigid supports and can be moved on a power driven second carriage, together with the other parts of the overall structure, in the direction of the second axis of travel.
The rigidity of the overall structure encompassing the rigid slide and the rigid supports holding the workpiece platen serves to permit the precise positioning of the workpiece to be machined and of the machining tools employed for that purpose. Operating the xe2x80x9cTRUMATIC(copyright) 500 ROTATIONxe2x80x9d involves the movement of a corresponding large structure and heavy weight in the direction of the second axis of travel.
It is the objective of this invention to reduce the mass that must be moved in the operation of the machine, while maintaining the same precise guiding and positioning of the workpiece(s) and/or of the machining tool(s).
It has now been found that the foregoing and related objects may be readily attained in a machine tool having a frame having upper and lower arms providing a throat therebetween and a workpiece processing station adjacent the open end of the throat. An elongated guide rail extends in a first axis perpendicularly to the throat, and a work support table is provided.
A first carrier extends along the guide rail, and a multiplicity of guide units are spaced along and movable on the carrier in the first axis. A multiplicity of workpiece clamping units are carried by the guide units, and the machine tool also includes drive means for moving the guide units with the clamping units on the carrier along the first axis whereby a workpiece clamped thereby may be moved in the first axis relative to the work support table.
The guide rail is movable in the throat along a second axis perpendicular to the first axis, and there are included a second carrier supported on the frame and extending in a second axis parallel to the throat. A multiplicity of guide elements is spaced along and movable on the second carrier and support the guide rail for movement in the second axis of the second guide rail.
At least one tool holder is mounted on one of the guide units and movable on the first carrier, and the work support table is supported on the guide elements of the second carrier for movement thereon. The guide units on the guide rail are connected to one another by at least one connecting element. The guide elements on the second carrier are connected to one another by at least one connecting element. The connecting elements may be a connecting bar, or a connecting plate.
The guide units are connected by a gear rack extending along the first carrier in the direction of the first axis, and the gear rack meshes with at least one drive pinion of a linear drive for moving the guide units on the first carrier in the direction of the first axis of travel. The guide elements on the second carrier are connected by a gear rack extending along the second carrier in the direction of the second axis of travel, and the gear rack meshes with at least one drive pinion of a linear drive for moving the guide elements on the second carrier in the direction of the second axis of travel.
The gear rack is attached to at least one connecting element which serves to connect associated guide units. The gear rack is attached to at least one connecting element which serves to connect associated guide elements. The second carrier comprises a platen with at least one guide member provided on the top surface of the platen for steering the guide elements on the second carrier in the direction of the second axis of travel. The guide units on the first carrier are slides which are consecutively tandem-joined in the direction of their movement. The guide elements on the second carrier are slides which are consecutively tandem-joined in the direction of their movement.
As will be appreciated, the mass that must be moved in the machine tool concerned in the direction of the axis of travel is reduced substantially, in a machine embodying the present invention. The workpiece support rail employed in corresponding prior art machines is replaced by an array of individually mounted guide units whose combined total mass is less than that of a corresponding prior art workpiece support rail. In the present invention, precise workpiece and tool positioning is obtained due to the rigidity of the carriage structure in conjunction with an appropriately precise mounting of the guide units of this invention on that carriage.
In the prior art designs, all support and clamping devices for the workpiece and for the machining tools are jointly mounted on a common component, that being the traditional support rail. In the present invention, these devices are spatially distributed, and this distribution of the guide and load transfer functions over several relatively compact guide units. This makes it possible to transfer the loads bearing on the individual guide units into the carriage structure next to their point of contact. This, in turn, given good rigidity of the overall structure encompassing the carriage and the guide units, assures good support and positioning of the workpiece and/or tool holding devices. Consequently, the machine tool does not need the rigid supports which are provided in the prior art designs for mounting the workpiece holders in the direction of the second axis of travel. This requires the separation of the movement of the first carriage from the transport of the workpiece platen.
Guide units can be used which have less bulk than the conventional rigid supports. Precise workpiece and tool positioning is obtained by means of the rigid second carriage and the design of the mounts for the guide units of the second carriage. The reduction in bulk and weight makes it possible to run the feed system with relatively fast acceleration, permitting high processing throughput rates in both cases.
The design concept of the new machine tool combines the advantage of relatively small weight to be moved in the direction of the first axis of travel and the advantage of relatively small weight to be moved in the direction of the second axis of travel.
Within the framework of the present invention, it is possible to equip each guide unit on the first carriage and/or each guide unit on the second carriage with its own directional drive. However, according to the present invention, the preferred machine design employs a common drive system for the several guide units.
It utilizes a simple structural design for the connection between the guide units on the first carriage and in the guide units on the second carriage by rack-and-pinion mechanism, which can also serve as part of the traversing drive for the various guide units. Also, the design is such that the driving force applied by the pinion to the corresponding rack section translates over a short distance into motive power for several of the guide units to be driven.